Brittle material rotating and aligning mechanism for use in a brittle material scribing and/or breaking apparatus

ABSTRACT

A brittle material rotating and aligning mechanism comprising a bearing, a rotary table and a driving mechanism and installed in the worktable of a brittle material scribing and breaking apparatus is disclosed to carry a brittle material, for example, a semiconductor wafer for scribing and breaking into individual dies. The driving mechanism uses a flexible transmission member to rotate the rotary table for the advantages of low installation cost and no requirement for a precision adjustment during installation and, preventing the occurrence of back lash or the production of particles due to friction between the transmission member and the driving wheel of the driving mechanism, or between the transmission member and the rotary table.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a brittle material rotating andaligning mechanism and more particularly to such a brittle materialrotating and aligning mechanism, which is practical for use in a brittlematerial scribing and breaking apparatus to carry the workpiece forscribing and breaking into individual pieces.

[0003] 2. Description of Related Art

[0004] In semiconductor foundries, high precision apparatus are neededfor high precision production without producing much amount ofparticles. A regular wafer scribing and/or breaking apparatus, forexample, the apparatus disclosed in U.S. Pat. No. 5,820,006, uses gearsto form a transmission mechanism for rotating the loaded semiconductorwafer for scribing and breaking. Because gears are rough devices,backlash tends to occur during engaging action between two gears. Whenthis backlash problem occurred, it affects the precision of the waferscribing and/or breaking apparatus. Further, the engaging action betweentwo gears may produce particles due to friction resistance. Particlesare harmful to semiconductor wafers.

[0005] Therefore, it is desirable to provide a brittle material rotatingand aligning mechanism that eliminates the aforesaid drawbacks.

SUMMARY OF THE INVENTION

[0006] It is the main object of the present invention to provide abrittle material rotating and aligning mechanism, which fixes a flexibletransmission member to a rotary table for enabling the rotary table tobe rotated by the flexible transmission member to carry the workpiece onthe rotary table to the desired angle for scribing/breaking. For theadvantages of low installation cost and no requirement for a precisionadjustment during installation and, for the effect of preventing theoccurrence of backlash or the production of particles during operation,the flexible transmission member is the best choice.

[0007] To achieve this and other objects of the present invention, thebrittle material rotating and aligning mechanism is comprised of abearing, a rotary table, and a driving mechanism. The bearing comprisesa first annular bearing element fixedly fastened to a worktable of abrittle material scribing and/or breaking apparatus, a second annularbearing element supported on the first annular bearing element, and asupplementary annular bearing element coaxially and fixedly fastened tothe second annular bearing element to secure the second annular bearingelement to the first annular bearing element and for enabling the secondannular bearing element and the supplementary annular bearing element tobe rotated relative to the first annular bearing element. The rotarytable is fixedly mounted on the second annular bearing element of thebearing, and the rotary table has a peripheral wall. The drivingmechanism comprises a flexible transmission member mounted on theperipheral wall of the rotary table, a driving wheel engaged with theflexible transmission member, and a motor adapted to drive the drivingwheel to rotate the flexible transmission mechanism and the rotarytable. Because the present invention uses a flexible transmission memberto rotate the rotary table, which carries the workpiece (semiconductorwafer), and because the transmission member used is flexible and fixedlyfastened to the rotary table, the present invention eliminates theoccurrence of back lash and the production of particles due to frictionbetween the transmission member and the driving wheel or rotary table.Further, the flexible transmission member is inexpensive to manufactureand easy to install. During installation of the flexible transmissionmember, no precision adjustment is needed.

[0008] The second annular bearing element and the supplementary annularbearing element are fixedly fastened together by screws, defining anendless groove. The first annular bearing element has a flange extendedalong the inner diameter thereof and inserted in the endless groove tosupport the second annular bearing element and the supplementary annularbearing element to be rotated relative to the first annular bearingelement. This structure of bearing is a sliding bearing. Alternatively,a ball bearing or needle bearing may be used instead of the slidingbearing. Further, a lubricating layer may be provided in between theendless groove and the flange of the first annular bearing element.

[0009] At least one fastening means may be used to fix the flexibletransmission member to the peripheral wall of the rotary table. Theflexible transmission member can be a timing belt. Alternatively, achain transmission mechanism may be used instead of a timing belt.Further, a tension wheel may be provided to control the tension of theflexible transmission member.

[0010] Other objects, advantages, and novel features of the inventionwill become more apparent from the following detailed description whentaken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 illustrates a brittle material rotating and aligningmechanism installed in a wafer scribing and breaking apparatus accordingto the present invention.

[0012]FIG. 2 is an exploded view of the brittle material rotating andaligning mechanism according to the present invention.

[0013]FIG. 3 is a section view of the rotary table and the bearingaccording to the present invention.

[0014]FIG. 4 is an assembly view of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0015] With reference to FIG. 1, a brittle material rotating andaligning mechanism is shown installed in a wafer scribing and breakingapparatus 8.

[0016] With reference to FIG. 2, the aforesaid brittle material rotatingand aligning mechanism is comprised of a bearing 2, a rotary table 3,and a driving mechanism 4.

[0017] Referring to FIG. 3 and FIGS. 1 and 2 again, the bearing 2comprises a first annular bearing element 21 fixedly fastened to the topof the worktable 1 of a wafer scribing and breaking apparatus 8 byscrews (not shown), the first annular bearing element 21 having a flange211 extended along the inner diameter, a second annular bearing element22 coaxially mounted on the first annular bearing element 21, asupplementary annular bearing element 221 fixedly fastened to the bottomside of the second annular bearing element 22 by screws (not shown) anddefining with the second annular bearing element 22 an endless groove222, which receives and supports the flange 211 of the first annularbearing element 21, for enabling the second annular bearing element 22and the supplementary annular bearing element 221 to be rotated relativeto the first annular bearing element 21. In order to smoothen the rotarymotion of the second annular bearing element 22 and the supplementaryannular bearing element 221 relative to the first annular bearingelement 21, a lubricating layer 23 is formed in between the endlessgroove 222 and the flange 211. According to this embodiment, the bearing2 is a sliding bearing. Alternatively, a ball bearing, needle bearing,or any suitable equivalent bearing may be used.

[0018] The rotary table 3 is fixedly fastened to the second annularbearing element 22 of the bearing 2 by screws 7, and driven by thedriving mechanism 4 to rotate relative to the first annular bearingelement 21. The driving mechanism 4 comprises a flexible transmissionmember 41, a motor 42, a driving wheel 43, and a tension wheel 44.According to this embodiment, the flexible transmission member 41 is atiming belt. Alternatively, a chain belt or the like may be used insteadof the timing belt. The motor 42 is fixedly mounted in a motor mount 46,which is fixedly fastened to the worktable 1 with a connecting plate 47.The driving wheel 43 is fastened to the output shaft 421 of the motor42. The motor mount 46 has an elongated sliding slot 461. An axle 49 isinserted through the elongated sliding slot 461. The tension wheel 44 ismounted on the axle 49. A lock 48 is provided for locking the axle 49 onthe motor mount 46. When the lock 48 unlocked, the tension wheel 44 canbe moved with the axle 49 along the elongated sliding slot 461 to adjustthe tension of the flexible transmission member 41. The flexibletransmission member 41 is mounted on the periphery wall 31 of the rotarytable 3. A fastening means 45 is provided to hold down the flexibletransmission member 41 on the periphery wall 31 of the rotary table 3.The fastening means 45 is comprised of a front packing strip 453, aclamp plate 451, and a rear packing strip 454. The clamp plate 451 isused to hold down the flexible transmission member 41 at first. If thewidth of the flexible transmission member 41 is narrow, the rear packingstrip 454 is placed on the top of the flexible transmission member 41,and then a screw 452 is installed to fix the front packing strip 453,the clamp plate 451, the rear packing strip 454 and the flexibletransmission member 41 together, keeping the flexible transmissionmember 41 fixedly secured to the periphery wall 31 of the rotary table3. Thus, the flexible transmission member 41 can be driven to rotate therotary table 3. After installation of the flexible transmission member41 in the periphery wall 31 of the rotary table 3, a part of theflexible transmission member 41 is wound round the tension wheel 44 foradjusting the tension of the flexible transmission member 41 andextended over the driving wheel 43.

[0019] Further, a workpiece holder 5 is located on the rotary table 3 tohold a brittle material, for example, a semiconductor wafer 9. Theworkpiece holder 5 is a ring member having a rubber film 52 stretchedtherein. The semiconductor wafer 9 is attached to the rubber film 52.When the semiconductor wafer 9 cut into individual dies, the individualdies thus obtained are adhered to the rubber film 52. The workpieceholder 5 has two locating notches 51 in the periphery. The rotary table3 has two locating pins 32 corresponding to the locating notches 51 ofthe workpiece holder 5. During installation, the workpiece holder 5 isattached to the rotary table 3, keeping the locating notches 51respectively secured to the locating pins 32, and then a vacuum suctionforce or magnetic attraction force is applied to fix the workpieceholder 5 to the rotary table 3.

[0020] Referring to FIG. 4, when the motor 42 started, the driving wheel43 is rotated with the output shaft 421 of the motor 42 to move theflexible transmission member 41, thereby causing the rotary table 3 tobe rotated, and therefore the semiconductor 9 is moved with theworkpiece holder 5 to the aligned position for scribing and/or breaking.According to this embodiment, the angle of rotation of the rotary table3 is effectively controllable. The front packing strip 453 is madehaving a L-shaped profile. At least two sensors 6 are installed in thefirst annular bearing element 21 of the bearing 2 and adapted to detectthe position of the L-shaped front packing strip 453 indicative of theangle of rotation of the rotary table 3. Alternatively, the sensors 6can be installed in the worktable 1 or other suitable locations. Thesensors 6 can be optics sensors, or limit switches. According to thisembodiment, the sensors 6 are optics sensors and the range of thesensing angle is 90°±10°.

[0021] As indicated above, the present invention uses a flexibletransmission member 41 to rotate the rotary table 3, which carries theworkpiece (semiconductor wafer) 9. Because the flexible transmissionmember 41 is flexible and fixedly fastened to the rotary table 3, thepresent invention eliminates the occurrence of back lash or theproduction of particles due to friction between the flexibletransmission member 41 and the driving wheel 43 or rotary table 3.Further, the flexible transmission member 41 is inexpensive tomanufacture and easy to install. During installation of the flexibletransmission member 41, no precision adjustment is needed

[0022] Although the present invention has been explained in relation toits preferred embodiment, it is to be understood that many otherpossible modifications and variations can be made without departing fromthe spirit and scope of the invention as hereinafter claimed.

What is claimed is:
 1. A brittle material rotating and aligningmechanism comprising: a bearing, said bearing comprising a first annularbearing element fixedly fastened to a worktable of a brittle materialscribing and breaking apparatus, a second annular bearing elementsupported on said first annular bearing element, and a supplementaryannular bearing element coaxially and fixedly fastened to said secondannular bearing element to secure said second annular bearing element tosaid first annular bearing element and for enabling said second annularbearing element and said supplementary annular bearing element to berotated relative to said first annular bearing element; a rotary tablefixedly mounted on said second annular bearing element of said bearing,said rotary table having a peripheral wall; and a driving mechanismadapted to rotate said rotary table, said driving mechanism comprising aflexible transmission member mounted on the peripheral wall of saidrotary table, a driving wheel engaged with said flexible transmissionmember, and a motor adapted to drive said driving wheel to rotate saidflexible transmission mechanism and said rotary table.
 2. The brittlematerial rotating and aligning mechanism as claimed in claim 1, whereinsaid second annular bearing element and said supplementary annularbearing element define an endless groove; said first annular bearingelement has a flange extended along the inner diameter thereof andinserted in said endless groove to support said second annular bearingelement and said supplementary annular bearing element to be rotatedrelative to said first annular bearing element.
 3. The brittle materialrotating and aligning mechanism as claimed in claim 1, wherein saidsecond annular bearing element and said supplementary annular bearingelement are fixedly fastened together by screws.
 4. The brittle materialrotating and aligning mechanism as claimed in claim 2, wherein saidsecond annular bearing element and said supplementary annular bearingelement are fixedly fastened together by screws.
 5. The brittle materialrotating and aligning mechanism as claimed in claim 2, wherein saidbearing further comprises a lubricating layer provided in between saidendless groove and the flange of said first annular bearing element. 6.The brittle material rotating and aligning mechanism as claimed in claim1, wherein said flexible transmission member is a timing belt.
 7. Thebrittle material rotating and aligning mechanism as claimed in claim 1,wherein said driving mechanism further comprises a tension wheel adaptedto adjust the tension of said flexible transmission member.
 8. Thebrittle material rotating and aligning mechanism as claimed in claim 1,wherein said driving mechanism further comprises at least one fasteningmeans adapted to fix said flexible transmission member to the peripheralwall of said rotary table.
 9. The brittle material rotating and aligningmechanism as claimed in claim 8, wherein said fastening means comprisesa front packing strip, a rear packing, a clamp plate sandwiched inbetween said front packing strip and said rear packing strip, and aplurality of screws fixing said front packing strip, said rear packingstrip, said clamp plate and said flexible transmission member to theperipheral wall of said rotary table.
 10. The brittle material rotatingand aligning mechanism as claimed in claim 9, wherein said front packingstrip has a L-shaped profile; said rotating and aligning mechanismfurther comprises at least two sensors adapted to detect the position ofsaid L-shaped front packing strip for controlling the angle of rotationof said rotary table.
 11. The brittle material rotating and aligningmechanism as claimed in claim 1, further comprising a ring-likeworkpiece holder located on said rotary table and adapted to hold abrittle material for processing.
 12. The brittle material rotating andaligning mechanism as claimed in claim 11, wherein said ring-likeworkpiece holder has at least one locating notch; said rotary tablecomprises at least one locating pin corresponding to the at least onelocating notch of said ring-like workpiece holder.
 13. The brittlematerial rotating and aligning mechanism as claimed in claim 1 furthercomprising at least one sensor adapted to detect the angle of rotationof said rotary table.
 14. The brittle material rotating and aligningmechanism as claimed in claim 1, wherein said driving mechanism furthercomprises a motor mount, which holds said motor, and a connecting plate,which secures said motor mount to the worktable table of the brittlematerial scribing and breaking apparatus.
 15. The brittle materialrotating and aligning mechanism as claimed in claim 14, wherein saidmotor mount has an elongated sliding slot; said driving mechanismfurther comprises a tension wheel movable in said elongated sliding slotand adapted to control the tension of said flexible transmission member.